Rotatable grinding and surfacing tool



P 1965 T. J. LEVEQUE 3,205,622

ROTATABLE GRINDING AND SURFACING TOOL Filed Feb. 25, 1963 2 Sheets-Sheet 1 IN VENTOR. 79 771 6 17746 Ve a/e Sept. 14, 1965 'r. J. LEVEQUE ROTATABLE GRINDING AND SURFACING TOOL 2 Sheets-Sheet 2 Filed Feb. 25, 1963 INVENTOR Tit/701 J7 Aev gz/c ri-: PM,

United States Patent 3,205,622 ROTATABLE GRINDING AND SURFACING TOOL Trefl'le J. Leveque, 16606 Glastonbury, Detroit, Mich. Filed Feb. 25, 1963, Ser. No. 260,482 7 Claims. (Cl. 5112t)) This invention relates to a rotatable grinding and surfacing tool or the like and, more particularly, to improvements in devices of this type wherein the sanding pad thereof has a compound orbital and rotary movement imparted thereto.

The invention has as one of its objects to provide a tool of this type in which the sanding pad is moved in an orbital path and wherein this orbital movement causes the sanding pad to be simultaneously rotated about its axis.

Another object of the invention is to provide simple but expedient means for rotating the sanding pad whereby this action of the sanding pad may be accomplished in a positive manner and without the addition of costly and complicated mechanism for the purpose.

Another important object of the invention is to provide a device of this type which is so reduced in the number and character of its component parts as to approach the ultimate in structural simplicity thereby creating an economy in its manufacture, assembly and maintenance.

In attaining the objects and advantages of the invention, means such as an eccentric shaft, is provided for moving the sanding pad in an oribtal path. Gear means, such as a V-pulley or a gear wheel, is carried by the eccentric shaft for orbital movement thereby. This gear means, during its orbital movement, engages a stationary complementary gear means carried by the housing of the device. If a V-pulley is employed, the stationary gear means comprises a V-belt. If a gear wheel is used, the stationary gear means comprises a ring gear. The V- pulley or gear wheel is connected to the sanding pad and, as the V-pulley or gear wheel is orbited relative to its complementary'gear means, the V-pulley or gear wheel is rotated, thus rotating the sanding pad. Thus, simple but elfective means is provided for accomplishment the purposes of the invention.

The various objects and advantages, and the novel details of construction of two commercially practical embodiments of the invention, will become more apparent as the description proceeds, especially when considered in connection with the accompanying drawings, in which:

FIGURE 1 is a sectional elevational view of a device constructed in accordance with this invention;

FIGURE 2 is an enlarged horizontal sectional view taken substantially on the plane indicated by line 22 in FIGURE 1;

FIGURE 3 is a vertical sectional view taken substantially on the plane indicated by line 33 in FIGURE 2; and

FIGURE 4 is a view similar to FIGURE 2 showing a modified form of construction.

In the embodiments of the invention herein illustrated there is shown a motor 10, which in the present instance is an air motor which is supplied with air under pressure through an air conduit 11 which extends through a handle 12 to the motor. The volume of air supplied to the motor may be controlled by a valve (not shown) actuated by a lever 13. The reference character 14 indicates a button-type control for an on-and-off valve (not shown), the button being actuated by depressing a hand lever 15 pivoted to the motor as at 16.

Extending from the motor 10 is a drive shaft 20. Sleeved on the shaft is a connecting or coupling member 21 which is keyed to the shaft 20 as at 22 and is secured against longitudinal displacement thereon by means of a set screw 23 or the like. The shaft 20 is concentric with a stationary part of the device, here shown as a housing 24 which is secured to the motor 10.

Arranged in the connecting or coupling member 21 is a bearing 25. This bearing 25 is arranged eccentrically of the axis of the drive shaft 20 so that when the coupling member 21 is rotated by the drive shaft, the bearing member 25 will travel in an orbital path. The coupling member 21 is provided with a counter weight 26 diametrically opposite the eccentric position of the bearing 25 to compensate for the eccentricity of the bearing member 25 and the driven shaft carried thereby.

Rotatably mounted in the bearing 25 is a driven shaft 27 which thus is arranged eccentric to the drive shaft 20 and is moved in an orbital path by the bearing 25.

Secured to the end of the driven shaft 27 is a work performing member indicated generally by the reference character 30. This work performing member may consist of a pad 31 to which is secured a sheet 32 of sand paper or the like. The pad 31 is reinforced by metal top plates 33 and 34 and a spacing washer is interposed between the plate 34 and the end of the driven shaft 27. The work performing element 30 is nonrotatably secured to the driven shaft 27 by means, for instance, of a machine screw 36 or the like. Thus, the work performing element 30 is moved in an orbital path by the orbital bearing 25 and the driven shaft 27.

The invention contemplates means for also rotating the work performing element 30 about its axis and this means, in the embodiment illustrated in FIGURES 1 to 3, comprises complementary gear means consisting of a V-pulley 40 keyed to the driven shaft 27 as at 41. The V-shaped periphery 42 of this V-pulley is adapted to engage a V-belt 43 secured to the stationary housing 24. The V-belt 43 preferably has a peripheral layer 44 of relatively soft material, such as foam or sponge rubber, or the like so that the V-belt member may be seated within the housing 24 and fixed thereto against relative rotation. As the orbiting V-pulley 40 travels in its orbital path, it engages the V-belt 43 and, because of the frictional contact between these parts, will rotate the V-pulley 40 and also the driven shaft 27 about the axis of the latter so as to rotate the work performing element 30.

Thus, while the work performing element or member 30 is moving in its orbital path, it is also positively rotated about its axis so that the area of engagement of, for instance, the sand paper 32 with the work piece is constantly changed. Thus, the effectiveness of the tool is enhanced and it may be used as a grinder and as a surfacing machine.

In the embodiment illustrated in FIGURE 4, the complementary gear means consists of a ring gear 50 secured to the housing 24 and a gear wheel 51 secured to the driven shaft 27. Thus, during the orbital movement of the driven shaft 27, the gear wheel 51 will engage the ring gear 50 to rotate the driven shaft 27, as in the previously described construction. Thus, the work performing element 30 will be positively rotated about its axis during its orbital movement so as to thus provide the desired compound movement to the work performing element.

In producing the compound movement, it will be noted from FIG. 4, that the gear wheel 51 has 15 teeth and the ring gear 50 has approximately 20 teeth. As a result of this small difference in the number of teeth on the gear elements, the gear wheel will lag 5 teeth each rotation from the prior position on the ring gear. That is to say, a tooth on the gear wheel 51 will back up one-third of the periphery of the ring gear each rotation of the gear wheel. This produces a hypocycloidal move- From the foregoing, it will be seen that there is pro-- vided a rotatable grinding and surfacing tool in which the work performing element or sanding pad is moved in an orbital path and at the same time rotated about its axis. This compound movement is accomplished by a construction which is so reduced in the number and character of its component parts as to approach the ultimate in structural simplicity, thereby creating an economy in its manufacture, assembly and maintenance.

While two commercially practical embodiments of the invention have been described and illustrated herein some-.

what in detail, it will be understood that various changes may be made as may come within the purview of the accompanying claims. 1

What is claimed is: 1 a 1. A gear drive mechanism for a hand tool for surface finishing workpieces comprising a motor having a drive shaft providing a protruding end; a housing rigidly secured to said motor into which said shaft end extends;

a coupling member fixed to said ,drive shaft end for rotation therewith; pinion gear, means mounted for rotation on said coupling member about an axis eccentric to the axis of said drive shaft, said pinion gear means being adapted to fixedly mount a work performing member; ring gear means fixed to said housing in position to drivingly engage said pinion gear means and to effect rotational movement of said pinion gear means about its axis during orbitalmovement of said pinion gear means about the axis of said drive shaft, the ratio of the radius of said ring gear means to the radius of said pinion gear means being less than two to one.

2. A hand tool for surface finishing workpieces comprising a motor having adrive shaft providing a protruding end; a housing rigidly secured to said motor, said drive shaft end extending into said housing; a coupling member fixed to said drive shaft end for rotation therewith; pinion gear means mounted for rotation on and with respect to said coupling member about an axis eccentric to the axis of said drive shaft; ring gear means fixed to said housing in position to drivingly engage said pinion gear means and to effect rotational movement of said pinion gear means about its axis during orbital movement of said pinion gear means about the axis of said drive shaft, the ratio of the radius of said ring gear means to the radius of said pinion gear means being less than two to one; and a rotational work performing member secured for rotation and orbital movement with said pinion gear. I

3. The hand tool of claim 2, wherein the diameter of the diameter of the ring gear means.

4. A hand tool for surface finishing workpieces comprising a motor support housing having an open end; motor means fixedly mounted in said housing with its drive shaft end disposed concentrically in said housing and protruding toward said open housing end; a coupling member fixed to said drive shaft end and formed with a bearing socket ecccntrically related to said drive shaft; a journal bearing including inner and outer races disposed in said bearing socket; an eccentric shaft nonrotatably mounted in said inner bearing race to undergo orbital movement upon actuation of said motor and protruding from said inner bearing race toward said open housing end; pinion gear means fixed to said eccentric shaft; ring gear means fixed to said. housing in position to drivingly engage said pinion gear means to effect rotational movement of said pinion gear means and said eccentric shaft during orbital movement of said eccentric shaft, said ring gear means and said pinion gear means having a radius ratio of less than two to one; and a rotational work performing member having a diameter greater than the ring gear diameter.

5. The hand tool of claim 4, wherein the pinion gear means comprises a fifteen tooth pinion gear and the ring gear means comprises a twenty tooth ring gear.

6, The hand tool of claim, 4, wherein'the rotational workperforrning member comprises an abrading disk the abrading elements of which undergo a hypocyclical movement to enhance the abrading action on the workpiece. 7

7. The hand tool of claim 4 wherein the rotational work performing member comprises a spacer washer disposed to abut the eccentric shaft end, a centrally apertured backing plate disposed to abut the spacer washer, a ring pad fixed .to said backing plate, a ring of sand paper fixed to said ring pad, and a machine screw and lock washer assembly having a threaded shank freely passing through the central aperture of said backing plate and threaded into said eccentric shaft and an enlarged head overlying said lock washer to clampingly secure said rotational work performing member to the end of said eccentric shaft.

LESTER M. SWINGLE, Primary Examiner. 

2. A HAND TOOL FOR SURFACE FINISHING WORKPIECES COMPRISING A MOTOR HAVING A DRIVE SHAFT PROVIDING A PROTRUDING END; A HOUSING RIGIDLY SECURED TO SAID MOTOR, SAID DRIVE SHAFT END EXTENDING INTO SAID HOUSING; A COUPLING MEMBER FIXED TO SAID DRIVE SHAFT END FOR ROTATION THEREWITH; PINION GEAR MEANS MOUNTED FOR ROTATION ON AND WITH RESPECT TO SAID COUPLING MEMBER ABOUT AN AXIS ECCENTRIC TO THE AXIS OF SAID DRIVE SHAFT; RING GEAR MEANS FIXED TO SAID HOUSING IN POSITION TO DRIVINGLY ENGAGE SAID PINION GEAR MEANS AND TO EFFECT ROTATIONAL MOVEMENT OF SAID PINION GEAR MEANS ABOUT ITS AXIS DURING ORBITAL MOVEMENT OF SAID PINION GEAR MEANS ABOUT THE AXIS OF SAID DRIVE SHAFT, THE RATIO OF THE RADIUS OF SAID RING GEAR MEANS TO THE RADIUS OF SAID PINION GEAR MEANS BEING LESS THAN TWO TO ONE; AND A ROTATIONAL WORK PERFORMING MEMBER SECURED FOR ROTATION AND ORBITAL MOVEMENT WITH SAID PINION GEAR. 